Exhaust silencer for internal-combustion engines



EXHAUST SILBNCER FOR INTERNAL COMBUSTION ENGINES J. NEIL Filed Anril1924 nected by means of any suitab Patented Aug. 9, 1927.

, UNITED STATES PATENT OFFICE.

JAMES NEIL, OF ANNIESLAND, GLASGOW, SCOTLAND.

EXHAUST SILENGER FOR INTERNAL-COMBUSTION ENGINES.

Application filed April 24, 1924, Serial No. 708,771, and in GreatBritain October 12, 1923..

My invention has reference to improvements in and relating to exhaustsilencers for internal combustion engines, and has for its object theprovision of an improved device, wherein the exhaust from an internalcombustion engine is passed into a chamber gradually so that it mayexpand and be discharged from said chamber into the atmosphere easilyand freely, in order that the noise attendant upon the shock of a bodyor volume of gases meeting the atmosphere by sudden or violent expulsionthrough the engine exhaust pipe may be eliminated or greatly reducedwhile the back pressure upon the gases due to the inertia of theatmosphere may also be reduced, thereby effecting an economy in the fuelused in said engine.

This invention consists of an exhaust silencer comprising an inner pipehaving its one end in open communication with the engine exhaust and itsother end in open communication with the atmosphere and a spirallycorrugated outer casing forming a spiral chamber around said inner pipe,said chamber being bounded by said pipe and by the spiral corrugation ofsaid outer casing. The inner pipe, which extends through the outercasing and projects from both ends of same, is formed with perforationsarranged spirally round the same. The corrugated outer casing may be ofconical formation and the spiral corrugation may be of increasing pitchso that the chamber around said inner pipe may have a cross-sectionalarea which increases from the inlet to the discharge. At a point nearthe discharge end the inner pipe is plugged. Between said plug and theend of the outer casing adjacent to same the inner pipe is formed withopenings so as to pass the gases from the end of the spiral chamber.into the end of the inner pipe and out to the atmosphere through theend of the inner pipe. The said plug may be of conical formation.

In order that my said invention and the manner of carrying the same intoeffect or practice may be'properly understood, I have hereunto appendedan explanatory drawing which is an elevation, partly in section, of anexhaust silencer as constructed according to this invention.

Referring to said drawing In carrying this invention into effect orpractice, the one end 6 of a pipe a is cony constructed coupling to theengine exhaust pipe. The,

other end 5 of the pipe at is open to the atmosphere. The pipe a isprovided with a plurality of perforations 0 arranged in the form of aspiral as shown.

Surrounding the pipe (1 is an outer casexternal surface of the casing isincreased which provides for increased cooling surface.

The corrugated casing cl may be, as shown,

of conical formation, that is, the diameter of the casing d at the endeof the pipe (1 may be smaller than the diameter at the other end.Preferably, the corrugations of the outer casing are formed asillustrated. Longitudinal sectlons of the corrugations are of similarconfiguration. The distance of each corrugation from the pipe a and thepitch of the spiral increases as the spiral corrugation is developedaround the said pipe so that a chamber of increasing area is providedaround the pipe a.

At or about the point 9 in the pipe a a division wall or plug 0 isarranged or fitted.

This plug may be of conical formation as shown so as to diffuse thegases. Between theplug and the adjacent end of the outer casing,openings a are formed in the inner pipe a.

The exhaust gases pass into the pipe a through the end 6 from theengine, then through the perforations 0 into the chamber f, back intothe pipe or through the openings n and out to the atmosphere through theend I).

i I claim:

1. An exhaust silencer for internal combustion engines formed of aperforated inner pipe and an outer casing having a helical corrugationdefining a helical chamber around said pipe; one end of said pipe beingopen to the engine exhaust and the other end of said pipe being open tothe atmosphere with a division between said ends substantially as hereinset forth.

2. Apparatus comprising a perforated inner pipe; means disposed in saidpipe for obstructing the passage of gases therethrou h; and a casingsurrounding said pipe ormed with a helical corrugation so as to form achamber with increasing cross-sectional area.

Ill?

3. Apparatus comprising a perforflied inner pipe and having a conedisposed within said pipe adjacent to one end thereof; and a helicallycorrugated outer casing forming a helical chamber around said pipe.

4. An exhaust silencer com-prising a pipe having a series ofperforations; and a helically corrugated" casing surrounding said pipe,said corrugations having an increasing pitch.

5. In combination, an exhaust pipe having a series of perforations; anda helically corrugated casing enclosing said pipe, the radius of saidhelix corrugation increasing with the length thereof.

6. An exhaust apparatus comprising a perforated pipe; and a helicallycorrugated casing enclosing said pipe, the pitch and radius of saidhelix increasing with the length thereof.

' 7 An exhaust silencer comprising a perforated pipe, having an endobstruction adjacent to one end thereof in the form of a cone with theapex thereof extending toward the inlet end of said pipe; and ahelically corrugated casing enveloping said pipe so as to form a helicalchamber for the gases passing through said perforations.

8. An exhaust silencer comprising a perforated pipe having an endobstruction adjacent to one end thereof in the form of a cone with theapex thereof extending toward the inlet end of said pipe; and ahelically corrugated casing enveloping said pipe so as to form a helicalchamber for the gases pass-' ing through said perforations, said pipehaving an opening intermediate the end of said casing and saidobstruction adapted to receive'the gases, whereby gases may be discharged from said casing.

JAMES NEIL.

